Z-Drag 3:1 System
How to set up a Z-Drag hauling system. The "Z-Drag" creates a three-to-one mechanical advantage hauling system which multiplies the pulling force on the hauling rope by a factor of three. This is accomplished with the use of carabiners which act as pulleys and allows for a person to pull a much heavier load than with a rope tied directly to an object.
The Z Drag needs to be set up and "manned" carefully. Everyone should leave their helmets and PFDs on for protection if working to free a boat on a river. The Z-Drag, although originated for rescue of boats pinned in a river, can be used to help you lift anything heavy. A person can be hauled up a cliff face, a snowmobile or ATV can be un-stuck or heavy items such as large game can be hoisted into the air from a tree for butchering. Learning to set up a Z-Drag correctly can help you lift anything heavy, with only a minimal amount of equipment.
The system starts with a good anchor point. A large well-set boulder or tree trunk can work well as can a car bumper or other sturdy, fixed object. The items then needed to build the system are quite simple and include the following: about 75-100 feet of good haul rope, about 12 feet of smaller diameter cordage (5-10mm is good) to be cut in two for making "Prusiks" (see below), a rope or webbing loop/sling for encircling the anchor point, and two strong carabiners (suitable for climbing).
Note that the mechanical advantage of the Z-Drag System can exert tremendous force. Pay special attention to the attachment point to the boat. The hauling force involved can easily rip out seats and other points of contact not meant for handling such force. Strong carabiners, preferably locking style (screw-down) should be used. If locking carabiners are not available, double up and use two at the same location, with the gates facing in opposite directions.
Once you have everything organized and ready follow the instructions below to rig the system.
Z Drag Setup Instructions
1. Secure a sling of rope or webbing around the anchor point. If making a sling from rope, tie the ends together with a Double Fisherman's Knot. If making a sling from webbing, tie the ends together using a Water Knot. Leave a little bit of slack to attach the first carabiner. This is anchor carabiner.
2. Secure one end of your haul rope to the load. If freeing a pinned boat, tie onto the far end of the boat if possible. Run the working end of the rope through the anchor carabiner.
3. Wrap your first Prusik Loop (click for instructions to tie a Prusik Loop) as far down the rope toward the load as possible. Clip the second carabiner through the prusik and run the working end of the rope through the carabiner. This is the traveling prusik.
4. Tie a second prusik loop on the haul line near the anchor carabiner and clip the loop into the carabiner. This is your brake prusik. As the haul rope is pulled keep the brake prusik in front of the brake carabiner. Anytime a rest is needed or if the haul rope is let go of, the brake prusik serves to maintain tension on the rope so no progress is lost. As the haul line is pulled in, advance the brake prusik.
5. Eventually the traveling prusik will reach the brake prusik. Maintain tension with the brake and slide the traveling prusik back out toward the load as far as possible. Resume pulling until the objective is reached.
